This paper investigates the route optimization of multicast session in a sparse-splitting optical network. The main objective is to minimize the total cost of wavelength channels utilized by the light-tree while satisfying required QoS parameters. In this paper, both the optical-layer constraints (e.g., optical signal power) and application-layer requirements (e.g., end-to-end delay and inter-destination delay variation) are considered as the QoS parameters. Integer Linear Programming (ILP) formulations to solve the optimal multicast routing problem with the given QoS parameters are presented.